Keller Geotechnical, winners at Ground Engineering Awards.
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At the 2009 Ground Engineering Awards in London, the Thrandeston Bog project won the coveted award for best UK project with a geotechnical value over £1M. The award was accepted by contractors Keller Geotechnical and Nuttal John Martin who worked with consultants Mott Macdonald and RD Geotech for the client Network Rail.
Construction of the original London to Norwich railway in 1847 had been problematic because the bog comprised over 10m of peat and very soft clays overlying chalk. There were repeated slope failures and embankment settlement therefore a solution was improvised, creating a raft of brushwood faggots across the bog upon which the embankment, 5m high and 650m long, was formed.
Keller’s innovative solution for the problem involved dry soil mixing of the peat and soft clay to stabilize the embankment. Representing the first use of dry soil mixing equipment in the UK in a live transport environment, substantial cost savings of over 50% of the original piled scheme were made, but came with the risk of track settlement. Network Rail accepted the soil-mixing technique, provided a comprehensive site trial was undertaken and the embankment was extensively monitored.
Commenting on the project GE editor Ruby Kitching said, “These companies and individuals demonstrated the importance of good ground engineering when it comes preserving our national infrastructure. Finding solutions which tackle slope failures efficiently, economically and in a sustainable and safe manner will mean the rail network continues to serve passengers for another 100 years. This solution was brilliantly suited and pushed to the forefront cutting edge thinking in geotechnics and ground engineering.”
Judges said that it was “A purely geotechnical project with a novel geotechnical solution that was sustainable and sensitive to its location.”
Dry soil mixing increases the strength of very soft soils. The technique involves injecting and then mixing cement powder into the soil to create columns of stronger material. For this project approximately 10,000 soil mix columns in panels along both sides of the embankment were installed.
Dr.Dan Adams, Keller’s Environmental Systems Manager accepted the award on Keller Geotechnical’s behalf.
